C4 Top-End Upgrades - A Plan Comes Together

Those of you with a yen for C4 tech are probably wondering what ever became of our Polo Green '96 coupe, which appeared poised last winter to take a giant leap toward dragstrip superstardom with the addition of Trick Flow's new Fast as Cast GenX head-and-cam package ("To Top It All Off," Feb.'10)? Unfortunately our enthusiasm for the project turned out not to be shared by members of the local Corvette-tuning community, no fewer than four of whom declined to take on the job of installing the parts after learning the age of the car.

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Such is the virtual pariah status to which the LT1 engine has sunk in the years since its retirement. Outmoded, down on power, and needlessly complex, the powerplant that did so much to restore the Corvette's performance luster in the early '90s is now treated by many as the mechanical equivalent of an end-stage Ebola patient-messy, intractable, and to be avoided at all costs.

Although we had originally hoped to give him a respite from sorting out our project-car hassles, we ultimately turned to Greg Lovell, at AntiVenom in Seffner, Florida, to handle the job. Unlike many newcomers to the Vette-fettling field, Lovell has been chin deep in these cars for most of his adult life, so he's well versed in the numerous idiosyncrasies afflicting older, less-popular models. After a minimum of cajoling, he agreed to take on our installation and let us hang around to photograph the affair.

In the pages that follow, we'll recap the major components of the package, bring you up to date on some new supporting items, and provide an overview of the install. In an upcoming issue (soon-we promise!), we'll be back to put the newly revitalized car through its paces at the track and on the dyno.

Since we were pulling the heads and intake off anyway, we decided to drop in a fresh set of TFS lifters (Summit PN TFS-21400002-16). While not mandatory on a low-mileage, roller-cammed car such as ours, this step is a worthwhile precaution given the relatively modest investment involved.

To clean up the engine bay a bit, we obtained a set of EGR block-off plates from UMI Performance (UMI PN 2100). The plates are machined from 6061 aluminum and install easily with a dab of high-temp RTV sealant. (Note: This is not an emissions-legal modification.)

As you might imagine, a job like this begins with a considerable amount of disassembly work, including the removal of the radiator...

...and intake manifold, as well as the headers (or exhaust manifolds), OptiSpark unit, and pulley assemblies.

With most of the ancillary gear out of the way, we can get a good look at the oil-encrusted front cover. Though unpleasant to behold, this type of leakage isn't out of the ordinary on an LT1 engine.

Moving on to the engine valley, installer Greg Lovell removes the lifter-retaining hardware...

...followed by the stock lifters.

Pulling off the front cover exposes the factory timing chain.

Once that's been removed, out comes the stock cam.

The next steps involve installing our TFS cam, followed by the GMPP Severe Duty timing set...

...and freshly cleaned front cover.

Now that the front of the engine is back together, it's time to pull the factory LT1 cylinder heads.

After laying the included gaskets in place, Lovell installs the new Fast as Cast GenX heads.

They're secured with beefy ARP bolts, which also come with the TFS package.

Lovell then drops in our fresh TFS lifters...

...and reinstalls the factory lifter-retaining hardware.

Adding oil directly into the lifter valley (rather than via the fill tube) effectively "pre-oils" the engine, allowing lubricant to coat critical engine parts as it drains into the pan. We used Royal Purple 10W-30 synthetic.

The remainder of the job involves installing any remaining engine parts, including, in our case, a set of TFS 1.6-ratio roller rockers...

...and the included 30-lb/hr fuel injectors.

This shot of the completed engine provides little evidence of the work that's taken place. Cowl-mounted bottle caps add critical car-guy cred.

Like any major engine modification, the TFS package requires custom, post-install PCM tuning to achieve an optimum balance of performance and driveability. We sent our car's computer off to Tony Gonyon (shown), at TunersInc. in Orange Park, Florida, who has extensive experience with the late C4's complex OBD-II brain. Once the recalibrated unit arrives back at VETTE HQ, we'll be ready to perform our usual battery of dyno and track testing.

Modifying an LT1 Corvette is not an easy task, especially with questionable parts. In this VETTE Teach, check out some of the most commonly chosen, best-used, alternative products that will make the modification much better and effecient. Check out the details and pictures at Vette Magazine. » Read More